Long Vector Execution Tests: Add packed data types

[alsepkow]

The tests currently only cover :bool, int16_t, uint16_t, int32_t, uint32_t, int64_t, uint64_t, float16_t, float32_t, float64_t

Need to add eg int8_t4_packed

See https://microsoft.github.io/DirectX-Specs/d3d/HLSL_SM_6_6_Pack_Unpack_Intrinsics.html

[damyanp]

@alsepkow / @V-FEXrt - need to confirm whether or not these packed types are valid as vector element types. At the moment DXC says "no". https://godbolt.org/z/9Eab46r97

(note: this godbolt link was using the wrong type)

[V-FEXrt]

I don't think they are, but I also don't think this is an LV question. This issue is raised outside of LV scope as well https://godbolt.org/z/9T8zTK7Pd

(note: this godbolt link was using the wrong type as it was based on the one in the previous comment)

[damyanp]

Packed types aren't valid element types for any vector (long or short).

[damyanp]

Although packed types are actually supported, in DXIL they are exactly the same as uint32 so we don't need to write any additional execution tests for them.